1. REVIEW OF STEEL DESIGN
KNOWLEDGE BASE REQUIRED:
STRENGTH OF MATERIALS
TIMBER DESIGN
SOIL MECHANICS
STEEL DESIGN

2. REVIEW OF STEEL DESIGN BASIC STEEL DESIGN REVIEW:
Review of AISC Construction Manual (cont):
Compact vs. Non- Compact
Compact Beam are rolled beam that can achieve
the plastic moment.
Stress Distribution of I Beam

3. REVIEW OF STEEL DESIGN BASIC STEEL DESIGN REVIEW:
Review of AISC Construction Manual (cont):
Compact Sections-
are symmetrical about the y-y axis
webs/flanges must have certain width-thickness ratios
(Spec Section - Table B5.1,P.5-36)
compression flange must be adequately braced
against lateral buckling
When the theoretical yield stress F’y is equal to or
exceeded by the yielding stress of 65ksi than the
section is compact.

4. REVIEW OF STEEL DESIGN BASIC STEEL DESIGN REVIEW:
Design Procedure for Bending(using Sx)
1. Determine the Maximum Bending Moment
2. Compute the Required Section Modulus based
on allowable stresses Fb=.66Fy (compact)
[equat. F1-1,Chapt. F1.1] or Fb=.60 Fy
(for non compact)[equat. F1-5,Chapt. F1.2]
3. Enter the ASD selection table and find the
nearest tabulated value of Sx. The lightest weight
and the most economical section that will serve for
the yield strength stated is in bold face, and should
be selected adjacent to or above the required Sx.
4. Check F’y column to be sure of compact section.
5. Check the lc & lu to make sure of adequate
bracing.

5. REVIEW OF STEEL DESIGN BASIC STEEL DESIGN REVIEW:
Note:For Members with Compact or Non-compact
sections.
Recall lc is the max. unbraced length in feet of the
compression flange at which the allowable bending
is taken at 0.66 Fy
Recall lu is the max. unbraced length in feet of the
compression flange for which allowable bending
stress may be taken at 0.60 Fy when Cb=1

6. REVIEW OF STEEL DESIGN BASIC STEEL DESIGN REVIEW: Recall l, lc, and lu
if l is the given length between lateral supports
then,
lc>l use Fb=.66Fy (assuming compact section)
lu>l>lc use Fb=.60Fy
l>lu use the charts of allowable moments in beams
(p to 2-212) where Cb=1
Note: Cb is the bending coefficient dependent upon
moment gradient (F1.3)
Cb=1
when the bending moment at any point within
an unbraced length is larger than that at both
ends of this length
when frames are braced against joint translation.
when considering a conservative value for cantilever

7. REVIEW OF STEEL DESIGN BASIC STEEL DESIGN REVIEW: Given:
Select a beam of Fy=36ksi steel subjected to a
bending moment of 125 kip-ft., having its compression
flange braced at 6 ft. intervals.
Solution:
Assume compact section, Fb=0.66Fy=23.8ksi
1. Maximum Bending Moment Given in Problem
2. Sx(reqd)=M/Fb=(125x12)/23.8=63 cu.in.
3. Nearest Tabulated Value
W16x
W12x
Since W16x40 is bold face, it is the lightest
suitable section that will serve for that yield strength.

8. REVIEW OF STEEL DESIGN BASIC STEEL DESIGN REVIEW: Given:
Select a beam of Fy=36ksi steel subjected to a
bending moment of 125 kip-ft., having its compression
flange braced at 6 ft. intervals.
Solution contd:
4. A check of the F’y column shows a dash, indicating
that F’y is greater than 65 ksi. Therefore, the shape
is compact.
5. From the table, Lc=7.4 ft. >6.0 ft. so the bracing is
adequate and the assumed allowable stress of .66Fy
is correct. Use W16x40

9. REVIEW OF STEEL DESIGN BASIC STEEL DESIGN REVIEW:
Recall: Mr is the beam resisting moment
if shape has compact sections
if shape has non compact flanges
Design Procedure for Bending(using Mr)
1. Enter the ASD selection table and find the
nearest tabulated value of Mr. The lightest weight
and the most economical section that will serve for
the yield strength stated is in bold face, and should
be selected adjacent to or above the required Mr.

10. REVIEW OF STEEL DESIGN BASIC STEEL DESIGN REVIEW:
2. Check F’y column to be sure of compact section.
3. Check the lc & lu to make sure of adequate
bracing.
4. Remember Mr is only valid for l<lc
Given:
Select a beam of Fy=36ksi steel subjected to a
bending moment of 125 kip-ft., having its compression
flange braced at 6 ft. intervals.
Solution:
Assume compact section, Fb=0.66Fy=23.8ksi
1. Enter Bending Moment Given in Problem
Nearest Tabulated Value
W16x k-ft
W12x k-ft
Since W16x40 is bold face, it is the lightest
suitable section that will serve for that yield strength.

11. REVIEW OF STEEL DESIGN BASIC STEEL DESIGN REVIEW: Given:
Select a beam of Fy=36ksi steel subjected to a
bending moment of 125 kip-ft., having its compression
flange braced at 6 ft. intervals.
3. Check F’y column to be sure of compact section.
OK the same as before
4. Check the lc & lu to make sure of adequate
bracing.
Lc=7.4ft > 6.0ft therefore Mr is valid
Use W16x40